It is well known that when optical signals are transmitted over an optical fiber, they are particularly susceptible to second order distortions. Indeed, these distortions become more pronounced with an increase in the length of the optical fiber. As is also known, however, from the disclosure of U.S. application Ser. No. 12/980,008 for an invention entitled “Passive Optical Network with Sub-Octave Transmission,” which is owned by the same assignee as the present invention, and which is incorporated herein by reference, the unwanted second order distortions in a transmitted optical signal can be effectively filtered out when the radio frequency carriers are selected from a sub-octave bandwidth. Consequently, a clearer signal is transmitted.
In addition to the clarity of received signals, many present-day networks also need to be able to handle increased traffic loads. A consequence of this is that the increased traffic will require the use of additional, different type transmission networks. In any event, good signal quality and a capacity to simultaneously transport many digital signals over an optical network is desirable.
In light of the above, it is an object of the present invention to provide a system and method for optically transporting a plurality of digital signals that increases the traffic capacity of an optical network by modulating the digital signals onto different modem-specific frequencies (fn) that are each predisposed for a sub-octave transmission. Another object of the present invention is to provide a system and method for “stacking” digital signals according to their respective carrier frequency (fn) onto a same optical signal of wavelength “λ”. Yet another object of the present invention is to provide a system and method that maintains an effective separation between digital signals as they are being transported over an optical fiber. Still another object of the present invention is to provide a system and method for optically transporting a plurality of digital signals over an optical fiber that is easy to use, relatively easy to manufacture, and comparatively cost effective.